Copper sulfate solutions can be produced from, for example, copper oxide which is dissolved in sulfuric acid (German patent No. 1,007,307) or by leaching metallic copper with a sulfuric acid solution in the presence of oxygen (German patent No. 1,036,240 and Ullmann's Enzyklopadie der Techn. Chemie, 3rd Edition, vol. 11, p. 249; 1960).
Metallic copper can also be leached by passing copper sulfate and sulfuric acid together with air through metallic bulk copper. At least part of the solution which traverses the bulk material is subjected to temperature equilibration and then is recycled to the bulk material while part of the solution is withdrawn as the product if desired (see U.S. Pat. No. 2,533,245).
Processes in which copper oxide is used as a starting material have the significant disadvantage that the copper oxide must be produced by a separate process step, for example, the atomization and simultaneous oxidation of the metallic copper.
Processes which involve the leaching of metallic copper with sulfuric acid or a sulfuric acid solution containing copper sulfate have the disadvantage that it is difficult to provide and maintain within the bulk material the uniform supply of oxygen which is essential for oxidation.
The difficulties increase as the particle size of the metallic copper decreases.
Increasingly, attention has been directed to the use of sections or particles of wire obtained from shredders as the starting material. Where such sections, pieces and particles of wire are used, it is virtually impossible to ensure a uniform flow of gas therethrough, thereby increasing the problems which have been encountered when oxidation with gaseous oxygen within the body of metallic bulk material is required.